Expressive writing (EW) is an intervention technique that has been shown to produce improvements in psychological and physical health in several controlled studies to date. The intervention calls for participants to write an essay, for 20 minutes at a time, on 3 successive days, expressing their thoughts and feelings about a traumatic experience. The positive health benefits of this intervention have been demonstrated in both healthy subjects, in terms of increases in subjective well-being and immune function and decreased health center visits, and clinic patients (i.e., asthmatics and rheumatoid arthritis patients), in terms of decreased physical symptoms. The mechanisms by which EW may exercise its beneficial effects are consistent with those that may underlie elevated blood pressure and hypertension. However, no study has yet examined the effects of EW on blood pressure. The proposed research will test the effects of an EW intervention on subsequent 24-hour ambulatory blood pressure (ABP) levels using a randomized controlled trial in which uncontrolled mild hypertensives are randomly assigned to the EW condition or a control condition. Post-intervention ambulatory BP monitoring will be performed at 1 and 4 months. On ABP assessment days, catecholamine levels will also be examined as an index of sympathetic activity through analysis of 24-hour urine samples. Chronic sympathetic activation is one proposed mechanism by which EW may operate, and measurement of pre- and post-intervention catecholamines will provide a test of that hypothesis. The EW participants will be further assigned randomly to a second EW intervention or to a control condition, permitting comparison of the effects of zero, one, and two administrations of the intervention on ambulatory BP. The content of written material will also be analyzed for insight terms that may predict the effectiveness of the intervention on subsequent ambulatory BP.